Triggered thyratron circuit



June 21, 1960 J. B. RICKETTS, JR., ETAL 2,942,160

TRIGGERED THYRATRON CIRCUIT Filed March 4, 1955 MAGNETIC OR +9OV I? RELAY COIL TRIGGER W -0l5 3300 m INPUT- IN VEN TORS JAMES B. RICKETTS JR.

ROBERT H. SCHAFER AGE NT 2,942,166 'rmccnaan THYRATRON cntcUrr James B. Ricketts, In, Br n Mawrjand Robert H.-

Schafer, Upper Darby, Pl.,- assignors to Burroughs Corporation, Detroit, Mlcln, acorporatlon of Filed Mar. 4, 1955, s01. No; 492,215 a c ai (cl. 311-142 This invention-relates to thyratron actuated relay circuits and more particularly it relates to relays responsive to pulses of short duration.

In operating electronic computers it is necessary to actuate electrical relays from short duration pulses in order to mechanically set up printer mechanisms or to etfect other control functions. In electronic computer. circuits, timing pulses are usually available having short duration. A typical pulse is a positive pulse volts in amplitude and 1V: microseconds in duration. In order to operate a relay from this pulse, it is necessary to pro vide a large current by means of a gaseous discharge device such as a 2D21 thyratron tube. However, the available pulse is not of sufiicient amplitude or duration to reliably fire thegaseous discharge device. In addition, the load circuits for the gaseous discharge tubes comprise solenoids which are highly inductive and therefore opposev initial surges of current. This causes difiiculty in building up sufficient discharge current to sustain ionization when a short impulse signal terminates in the input circuit, and further prevents reliable operation in the presence of pulse actuation signals for gaseous discharge devices.

It is, therefore, an object of this invention to provide thyratron actuated relay circuits for operation with input pulses of short duration.

A general object of this invention is to produce im proved triggered thyratron circuits.

In accordance with the invention, therefore, the operation of thyratron actuated relay circuits, which are triggered with input pulses of short duration, is made more reliable by providing a pulse lengthening input circuit for the thyratron, and an auxiliary current source for sustaining ionization during initial current surges through the thyratron. In one embodiment, the input} 2,942,160 Patented June 21, 1960 capacitor 9 which chargeis retained for a substantially longer period of time than the duration of the pulse because of the higher resistance discharge path provided by the resistor 10. The tube is initially-maintained at cut-off by the 14 volt bias at terminal 11.

Since the relay coil or solenoid 12 presents a high fimpedance to initial current surges, the capacitor '13 and resistor 14 are connected in series in shunt across the thyratron. During the time the thyratron tube is cut otf, the capacitor 13 is charged by the +250 volt source 5 through the relay coil 12. When the thyratron tube is 'ffired, capacitor 13 discharges therethrough, thereby serving as a current source effective to maintain initial conduction through the tube.

" In this manner, ionization is sustained until the relay coil 12 passes sutficient tube current to maintain ionizacircuit comprises a storage capacitor connected in series with a diode rectifier device so poled that the capacitor may be charged therethrough 'by the input pulse to thereby store the actuating signal for a longer period than the duration -of the pulse. auxiliary current source circuit comprises a capacitor and resistor connected in series-across the thyratron. When the thyratron is in cut-oft condition, the capacitor 13 is charged by the +250 volt source through the relay coil 12. When the thyratron is initially fired, capacitor 13 discharges through the tube, thereby providing current to sustain ionization until the tube current through the inductive load circuit rises sutiiciently to sustain ionization.

A circuit operable in accordance with the invention is shown schematically in the single figure of the drawing together with typical circuit values for operation with positive 10 volt pulses, 1% microseconds in duration.

The input trigger pulses are applied at terminal 5 and are stepped up by transformer 6 to produce approximately 40 volts positive signals at the control grid electrode 7 of the 2D21 thyratron. The positive input pulses cause current flow through the diode 8 to charge the An embodiment of the tion.

In order to reset the thyratron circuit for further triggering, a relay 16 is provided for selectively increasing the impedance presented to the current path of the tube. Thus, when the relay 16 is energized, the short across resistor 18 is removed and the resistor 18 is effectively connected in series in the current path of the tube. The tube current decreases and the ionization is extinguished. The cut-oft bias at terminal 11 maintains the tube in cut off condition until a further trigger pulse is received.

Therefore, in accordance with the present invention, a novel system is provided for reliably operating a highly inductive relay or other circuit from short duration pulses. Those features of novelty describing the invention are therefore set out in particularity in the following claims.

What is claimed is:

1. A system for actuating a high inductance electrical relay in response to short duration input pulses, said system comprising, in combination; a gaseous discharge tube having anode, cathode and control-grid electrodes; bias means for normally biasing said tube below. cut off; means for connecting the inductive winding of said relay between the anode of said tube and the positive terminal of a source of direct-current voltage; means for connecting the cathode of said tube to the negative terminal of said direct-current voltage source; a first capacitor and a first resistance serially coupled in shunt across said tube between said anode and cathode electrodes, said first capacitor charging through said relay winding to substantially the voltage of said direct-current voltage source during the period that said tube is cut off; a pulse-lengthening input circuit for said tube, said circuit comprising a second capacitor connected between the grid and cathode electrodes of said tube and means including a diode shunted by a second resistance for connecting a source of input pulses to the grid of said tube to fire said tube, said diode being so poled that said second capacitor is charged through said diode by the input-pulse current but, following the termination of the input pulse, is discharged through said shunt second resistance, the impedance of said shunt second resistance being high relative to the forward impedance of said diode, said first capacitor discharging through said tube when said tube is fired, said first-capacitor discharge current through said tube being elfective to maintain the tube ionized until the tube current through said relay inductance has risen sufficiently to maintain ioniza- Hon.

2. Apparatus as claimed in claim 1 characterized in that a voltage step-up transformer is connected between said input-pulse source and said pulse-lengthening input circuit.

3. A system for actuating a high inductance electrical relay in response to short duration input pulses, said system comprising, in combination; a gaseous discharge tube 3 h i ainputan o t te cctt s evb a mean iq b ing said tube normally into non-conduction; means for connecting the inductance winding of said relay between current mi' sa dir ctatlrtcn q ta t-sqm idl :P iQ -a'th a tu i nonondu in le en n -inp fl rc wqm t si za-s wn ,9 15a9 t H s pnl ttha s 11599 i a iwn 'q g therethrough by input-pulse current but,- is ;di s,cha:rged

thr ug gsaiyd 9.1m e qn r-xet stan th im edang of. s i hun se qn redefi e ein relat t0 t zesaaaa teo .tq ward ,i mp ne of said asymmetrically conducting device, said first capacitor discharging through said tube when said tube is fired, said capacitor discharge current through said tube being effective to maintain the tube ionized until the tube current through said relay winding has risen sufficiently tomaintain such ionization.

'tisattsaass tQite tmthet l a thie nate ...UN IED tTATE J- AIEN'ES 3 3 r-r' 21-3111 17-, p I 9 3 4 "1';980;707 "Stansbury -Novst3,-1934 2,177,843 gegley Qct. 31, 1939 2,287,926 Zepler June 30; 1942 2,306,237 Wol-fner -1 Dec. 22, 1942 2,510,742 Ely June 6, 1950 2,584,758 Stutsman Feb. 5, 1952 

